Nifedipine Treatment for Hypertension is Associated with Enhanced Lipolytic Activity and Accelerated Clearance of Postprandial Lipemia.

Hypertension, advanced age, postprandial hyperlipidemia, and insulin resistance are major risk factors for atherosclerosis. The calcium channel blocker nifedipine is reported to ameliorate insulin resistance possibly by activating PPARγ. This is expected to become accentuated in elderly individuals due to age-related insulin resistance. Insulin resistance modulates lipoprotein metabolism. Therefore, we reasoned that nifedipne offers the potential for improving postprandial lipemia in association with increasing age. We studied the effect of nifedipine on fasting lipids, postprandial lipemia, insulin sensitivity, and plasma lipolytic activity in 24 and 15 hypertensive subjects aged 70-75 years and 40-45 years, respectively. As expected, nifedipine significantly lowered systolic and diastolic blood pressure. Nifedipine decreased fasting triglyceride level (23%) and increased HDL-C (15%) in the elderly group. At baseline, postprandial triglyceride levels were remarkably elevated in elderly compared to younger patients (1 288±798 vs. 501±260 mg·dl(-1)·h, p<0.05), as was retinyl palmitate (surrogate marker for intestinally-derived cholesterol) in the chylomicrons (45.0±26.5 vs. 23.4±10.6 mg·l(-1)·h, p<0.05) and chylomicron remnant (15.2±5.4 vs. 11.7±4.7 mg·l(-1)·h, p<0.05) fractions. Importantly, while the level of chylomicron remnants in the group of younger subjects remained unchanged after treatment, nifedipine was associated with a significantly decreased chylomicron remnants retinyl palmitate in the elderly group, which dropped to levels, observed in younger subjects. This was accompanied by enhanced insulin sensitivity and augmented plasma lipolytic activity. The present work suggests that nifedipine has favorable metabolic effects that are beyond the known enhancement of insulin sensitivity. The improvement in postprandial lipidemia by nifedipine may add to its anti-atherogenic effects in hypertensive patients.

The Effect of Klotho Treatment on Atherogenesis, Blood Pressure, and Metabolic Parameters in Experimental Rodent Models.

Klotho is a transmembrane protein, expressed mainly in the kidneys and the choroid plexus. The extracellular domain of klotho is composed of 2 internal repeats, KL1 and KL2, which can be cleaved and act as hormones. Klotho-deficient mice develop a phenotype resembling human aging. Laboratory and clinical data suggest a favorable effect of klotho on atherosclerosis, high blood pressure, and metabolic syndrome. Therefore, we aimed to study the effect of klotho treatment on atherogenesis, blood pressure, and metabolic parameters in experimental rodent models. Fructose-fed Sprague-Dawley rats (metabolic syndrome model) and apolipoprotein E (apoE -/-) knock-out mice (atherosclerosis model) were treated with either klotho or its active domain KL1. In apoE -/- mice, klotho unexpectedly elevated plasma cholesterol and triglyceride levels compared to the control group. Yet, it did not increase the aortic sinus atherosclerotic lesion area. In fructose-fed Sprague-Dawley rats, klotho treatment did not lower blood pressure or plasma triglyceride levels. Although KL1 treatment did not lower blood pressure or plasma insulin levels, it significantly reduced the elevation of total plasma triglyceride levels (from 2.3-fold to 1.6-fold, p<0.05) due to lower triglyceride-rich VLDL levels. Klotho did not show any beneficial effects on atherosclerosis and components of the metabolic syndrome and was associated with increased plasma cholesterol levels. On the other hand, treatment with KL1 may lower plasma triglyceride levels independent of insulin. Additional studies are required in order to decipher the complex role of klotho and its active domains in the regulation of plasma lipid levels.

VB-201, an oxidized phospholipid small molecule, inhibits CD14- and Toll-like receptor-2-dependent innate cell activation and constrains atherosclerosis.

Atherosclerosis is an inflammatory disease of the vascular wall. Activated monocytes and dendritic cells (DC) in the intima layer of the vasculature promote atherogenesis. Toll-like receptor (TLR)-2 and TLR-4, which are predominantly expressed on these cells and mediate their activation, are essential for atherosclerosis development. In this study we demonstrate that VB-201, an oxidized phospholipid (Ox-PL) small molecule, inhibits TLR signalling restricted to TLR-2 and TLR-4 in human and mouse monocytes and DC. Mechanistically, we show that VB-201 binds directly to TLR-2 and CD14, the TLR-4 co-receptor, to impair downstream cues and cytokine production. In a rabbit model, oral administration of VB-201 constrained atherosclerosis progression. This effect was not due to reduced cholesterol abundance, as hyperlipidaemia was sustained. We suggest that VB-201 may counter inflammation where TLR-2 and/or CD14 complicity is essential, and is therefore beneficial for the treatment of atherosclerosis.

The effect of α-linolenic acid enrichment in perinatal diets in preventing high fat diet-induced SCD1 increased activity and lipid disarray in adult offspring of low density lipoprotein receptor knockout (LDLRKO) mice.

The present study examined the effects of maternal perinatal dietary ALA enrichment on the high fat diet (HFD)-induced lipid disarray in the adult offspring of low density lipoprotein receptor knock-out (LDLRKO) mice. Female LDLRKO mice received, during pregnancy and lactation, isocaloric diets with either corn oil, RD, or flax oil, ALA. The weaning offspring was given a regular chow diet for a washout period of eight weeks, which was followed by HFD for eight weeks. Plasma and liver lipids and SCD1 activity were then analyzed. The HFD-fed RD adult offspring had substantially higher plasma cholesterol levels than the HFD-fed ALA offspring (15.7 versus 9.7 mmole/l, p<0.00001) and non-alcoholic fatty liver disease (NAFLD) (65.0 versus 23.9 mg/g lipids, p<0.00001). Liver lipids oleic acid (OA) content and monounsaturated to saturated fatty acids (MUFA/SAT) ratio, were two times lower in RD compared to ALA (p<0.0001). The threefold HFD-induced SCD1 raised activity (p<0.00001), and OA produced from SA, observed in RD adult offspring were prevented by perinatal ALA. In conclusion, the resilience of SCD1 to HFD- induced increased activity may account for the beneficial effects of perinatal ALA dietary enrichment in preventing NAFLD and hypercholesterolemia from occurring in adult LDLRKO offspring mice.

Specific induction of tumor neovasculature death by modified murine PPE-1 promoter armed with HSV-TK.

BACKGROUND: One strategy to increase tissue specificity of gene therapy is to use promoters or enhancers. OBJECTIVES: (1) To enhance the selectivity of a murine preproendothelin-1 (PPE-1) promoter in tumor angiogenesis by using a positive endothelial transcription-binding element. (2) To test the specificity and efficiency of the modified PPE-1 promoter [PPE-1(3X)] in vitro and in vivo by using reporter genes, and the therapeutic gene herpes simplex virus-thymidine kinase (HSV-TK) in a mouse model of Lewis lung carcinoma (LLC). RESULTS: The modified PPE-1 promoter specifically induced expression in the tumor angiogenic vascular bed with a 35-fold higher expression compared to the normal vasculare bed of the lung. Thus, when the HSV-TK gene controlled by the modified PPE-1 promoter was used systemically, it induced tumor-specific necrosis, apoptosis and mononuclear infiltrates, leading to massive destruction of the neovasculature of the pulmonary metastasis, which suppressed metastasis development. CONCLUSIONS: These results show that an adenoviral vector armed with HSV-TK controlled by the endothelial-selective murine PPE-1(3X) promoter is efficient and safe to target tumor neovasculature.

Targeting gene expression to the vascular wall in transgenic mice using the murine preproendothelin-1 promoter.

To develop a system for overexpressing genes in the vascular wall, we created transgenic mice using the reporter gene luciferase and the murine preproendothelin-1 promoter. In vitro analysis suggested that the murine 5'-flanking region contained endothelial-specific elements in a 5.9-kb fragment. Five transgenic mice colonies established from independent founders all exhibited the highest level of luciferase activity in the aorta with up to 8,540 light units per microgram of protein. Immunohistochemistry with anti-luciferase antisera revealed high levels of expression in the endothelial cells of both large and small arteries and lower levels of expression in veins and capillaries. Significant expression was also seen in arterial smooth muscle cells and in select epithelial surfaces which is consistent with the known distribution of endothelin-1 in mammals. The further demonstrate the targeting capability of this system, we overexpressed the lipid-peroxidating enzyme, human 15-lipoxygenase, in the vessel wall of transgenic mice. As with luciferase, expression of active enzyme and immunohistochemical localization in vascular cells were documented in transgenic animals. Hence, this new system can be used to direct expression of molecules to the vascular wall for the purpose of examining the biological significance of either overexpression or inhibition of select proteins.

Requisite role for interleukin-4 in the acceleration of fatty streaks induced by heat shock protein 65 or Mycobacterium tuberculosis.

Atherosclerotic lesions can be induced in rabbits and mice immunized with heat shock protein 65 (HSP65). In the current study, we investigated the role of interleukin (IL)-4 in the HSP65- and Mycobacterium tuberculosis (MT)-induced models that exhibit an inflammatory phenotype. Fatty streak formation in IL-4-knockout (IL-4 KO) mice immunized with HSP65 or MT was significantly reduced when compared with lesions in wild-type C57BL/6 mice. However, when injected with control (HSP-free) adjuvant, no differences were evident in the lesion size between wild-type and the IL-4 KO mice. Next, we studied comparatively the extent of humoral and cellular immune responses to HSP65 in the IL-4 KO and wild-type mice, as those are thought to be influential in murine atherosclerosis. Anti-HSP65 antibody levels were reduced in the HSP65-immunized IL-4 KO mice as compared with their wild-type littermates, whereas no differences were evident between the groups with respect to the primary cellular immune response to HSP65. Other than the absence of IL-4 in the knockout mice, the pattern of secreting cytokines interferon-gamma and IL-10 in concanavalin A-primed splenocytes was similar between the groups. HSP65-primed inguinal lymphocytes from IL-4 KO mice immunized with HSP65 secreted higher levels of interferon-gamma (previously shown to be proatherogenic in vivo) as compared with their wild-type controls. 12-/15-Lipoxygenase expression, known to be regulated by IL-4 and to contribute to murine atherosclerosis, in the lesions was not influenced by the immunization protocol used or by IL-4 disruption. Thus, IL-4 may prove a principal cytokine in the progression of early "inflammatory" atherosclerotic lesions and may serve as a target for immunomodulation.

Patients with Glanzmann thrombasthenia lacking platelet glycoprotein alpha(IIb)beta(3) (GPIIb/IIIa) and alpha(v)beta(3) receptors are not protected from atherosclerosis.

BACKGROUND: Platelets have been suggested to play a role in the early development of atherosclerosis. As one test of this hypothesis, we assessed whether patients with Glanzmann thrombasthenia who lack platelet glycoprotein alpha(IIb)beta(3) (GPIIb/IIIa) complexes or both alpha(IIb)beta(3) and the more ubiquitous alpha(v)beta(3) cell membrane complexes are protected from development of atherosclerosis. METHODS AND RESULTS: Seven patients with Glanzmann thrombasthenia, 45 to 66 years of age, underwent bilateral carotid artery ultrasonography and screening for risk factors of atherosclerosis. Findings consistent with early atherosclerosis evaluated by measurement of intima-media thickness and presence of atherosclerotic plaques were observed in 6 of the 7 patients. Intima-media thickness values higher than the 75th and 90th percentiles of age- and sex-matched white control subjects of the Atherosclerosis Risk in Communities (ARIC) study were observed in 30 and 8 of 56 carotid artery measurements, respectively. Five of the 6 patients with signs consistent with early atherosclerosis lacked both alpha(IIb)beta(3) and alpha(v)beta(3) complexes and 1 only lacked alpha(IIb)beta(3). CONCLUSIONS: Glanzmann thrombasthenia does not protect affected individuals from development of atherosclerosis.

Adoptive transfer of beta(2)-glycoprotein I-reactive lymphocytes enhances early atherosclerosis in LDL receptor-deficient mice.

BACKGROUND: It has been proposed that autoimmune factors can influence the progression of atherosclerosis. We have previously shown that immunization of LDL receptor-deficient (LDL-RD mice) with beta(2)-glycoprotein I (beta2GPI; a principal target of "autoimmune" antiphospholipid antibodies) enhances early atherosclerosis. In the present study, we tested the hypothesis that adoptive transfer of beta2GPI-reactive T cells can accelerate fatty streak formation in LDL-RD mice. METHODS AND RESULTS: LDL-RD mice were immunized with human beta2GPI. An additional group of mice were immunized with beta2GPI and boosted with the same antigen 3 weeks later. Control mice with immunized with human serum albumin. Lymphocytes obtained from the draining lymph node cells or from splenocytes of beta2GPI- or human serum albumin-immunized mice were stimulated in vitro with beta2GPI or with the mitogen concavalin A, respectively. The cultured lymphocytes were transferred intraperitoneally to syngenic LDL-RD mice, and the mice were fed a high-fat "Western" diet for 5 weeks until death. Mice injected with lymphocytes from draining lymph nodes or spleens of beta2GPI-immunized animals displayed larger fatty streaks than those induced by control treated animals. T-cell-depleted splenocytes from beta2GPI were unable to promote lesion formation in the mice. CONCLUSIONS: The present study provides the first direct evidence for a role of antigen (beta2GPI)-reactive T cells in the promotion of fatty streaks in mice.

12/15-Lipoxygenase gene disruption attenuates atherogenesis in LDL receptor-deficient mice.

BACKGROUND: Human 15-lipoxygenase (LO) and its murine analogue 12/15-LO are capable of directly oxidizing esterified fatty acids in lipoproteins and phospholipids. Because these oxidized products possess atherogenic properties, it was suggested that LOs may be involved in enhancing atherogenesis. Previous in vivo tests of the role of LOs in atherogenesis animal models, however, have yielded conflicting results. METHODS AND RESULTS: Aiming to study the role of the 12/15-LO in murine atherogenesis, we crossed LDL-receptor-deficient mice (LDL-R(-/-)) with 12/15-LO-knockout mice and evaluated plaque formation 3 to 18 weeks after initiation of a high-fat diet. Atherosclerotic lesions were considerably reduced in the LDL-R/12/15-LO-double-knockout mice compared with LDL-R(-/-) mice at 3, 9, 12, and 18 weeks, at the aortic root as well as throughout the aorta. The cellular composition of plaques from mice deficient in 12/15-LO did not differ with respect to macrophage and T-lymphocyte content compared with plaques from 12/15-LO littermates. CONCLUSIONS: 12/15-LO plays a dominant role in promoting atherogenesis in LDL-R(-/-) mice.

Immunolocalization of beta2-glycoprotein I (apolipoprotein H) to human atherosclerotic plaques: potential implications for lesion progression.

BACKGROUND: beta2-Glycoprotein I (beta2GPI) is a major antigenic target of antiphospholipid antibodies, which possesses natural anticoagulant properties. The aim of the present study was to determine its presence and localization within human atherosclerotic plaques and to study its association with endothelial cells and monocyte macrophages in vitro. METHODS AND RESULTS: Human atherosclerotic lesions were obtained after carotid endarterectomies and studied immunohistochemically with anti-beta2GPI as well as antibodies to CD4/CD8, macrophages, and adhesion molecules. In vitro, human umbilical vein endothelial cells (HUVECs) and U937 (myelomonocytic cell line) cells were investigated for their ability to associate with radiolabeled beta2GPI. We found beta2GPI to be abundantly expressed within the subendothelial regions and intimal-medial borders of human atherosclerotic plaques and to colocalize with CD4-positive lymphocytes. This observation was confirmed by Western blot applied on homogenates of atherosclerotic lesions with anti-beta2GPI antibodies. Both HUVECs and U937 cells bound labeled beta2GPI, and the process was inhibited by oxidized LDL and not by native LDL. CONCLUSIONS: The abundant presence of human beta2GPI within the lesions, its association with endothelial cells and macrophages, and its colocalization with CD4-positive lymphocytes suggests that it may serve as a target for an immune-mediated reaction that can influence lesion progression.

Effect of hyperglycemia and hyperlipidemia on atherosclerosis in LDL receptor-deficient mice: establishment of a combined model and association with heat shock protein 65 immunity.

Diabetes and atherosclerosis have been proposed to be influenced by immune and autoimmune mechanisms. A common incriminated antigen in both disorders is the heat shock protein (HSP)-60/65. In the current study, we established a model combining hyperglycemia with hyperlipidemia in LDL receptor-deficient (LDL-RD) mice and assessed its possible influences on lipid profile, HSP60/65, and atherogenesis. LDL-RD mice were injected either with streptozotocin to induce hyperglycemia or with citrate buffer (control). When hyperglycemia was induced, both study groups were challenged with a high-fat (Western) diet for 6 weeks. Plasma fasting glucose, lipid profile, and antibody levels to HSP65 and oxidized LDL were assessed. At death, the spleens from both groups were evaluated for their proliferative response to HSP65 and the consequent cytokine production. The extent of atherosclerosis was assessed at the aortic sinus. Plasma glucose, cholesterol, and triglyceride levels were elevated in mice injected with streptozotocin compared with control mice. Atherosclerotic lesions were significantly larger in the streptozotocin-injected hyperglycemic LDL-RD mice (132 +/- 23 x 10(5) microm2) in comparison to their normoglycemic litter-mates (20 +/- 6.6 x 10(5) microm2; P < 0.0001). Both humoral and cellular immune response to HSP65 was more pronounced in streptozotocin-injected mice. When challenged with HSP65 in vitro, splenocytes from streptozotocin-injected mice favored the production of the T-helper (TH)-1 cytokine gamma-interferon. In conclusion, we have established a mouse model that combines hyperglycemia with diet-induced hyperlipidemia in LDL-RD mice and studied its effect on atherosclerosis progression. The accelerated atherosclerotic process is associated with heightened immune response to HSP65 and a shift to a TH1 cytokine profile.

Cellular and humoral immune responses to heat shock protein 65 are both involved in promoting fatty-streak formation in LDL-receptor deficient mice.

OBJECTIVES: This study was designed to determine the role of cellular and humoral immune responses to heat shock protein 65 (HSP65) in murine atherosclerosis. BACKGROUND: Inflammatory processes appear to influence the progression of atherosclerosis. Immunization with HSP65 was previously shown to induce arteriosclerosis in rabbits and to enhance fatty-streak formation in mice. However, it has not been demonstrated directly whether HSP65-reactive antibodies and lymphocytes are separately capable of influencing lesion formation. METHODS: Low density lipoprotein-receptor deficient (LDL-RD) mice were immunized with HSP65 or control bovine serum albumin (BSA). Lymph-node cells, splenocytes and immunoglobulin G (IgG) were obtained from the immunized mice and transferred separately to six groups of syngenic LDL-RD mice. RESULTS: Adoptive transfer of HSP65-reactive lymph node cells increased fatty-streak formation in comparison with mice treated with BSA-primed cells. Similarly, transfer of splenocytes reactive with HSP65 led to enhanced fatty-streak generation compared with mice injected with BSA-sensitized splenocytes. Repeated intraperitoneal administration of IgG from serum of HSP65-immunized mice (every 10 days) enhanced fatty-streak formation in mice in comparison with their anti-BSA-IgG injected littermates. CONCLUSIONS: Antibodies and lymphocytes reactive to HSP65 promote fatty-streak formation in mice, providing direct evidence for the proatherogenic properties of cellular and humoral immunity to HSP65.

Overexpression of 15-lipoxygenase in vascular endothelium accelerates early atherosclerosis in LDL receptor-deficient mice.

To study the possible role of the human lipid-oxidizing enzyme 15-lipoxygenase (15-LO) in atherosclerosis, we overexpressed it specifically in the vascular wall of C57B6/SJL mice by using the murine preproendothelin-1 promoter. The mice overexpressing 15-LO were crossbred with low density lipoprotein (LDL) receptor-deficient mice to investigate atherogenesis. High levels of 15-LO were expressed in the atherosclerotic lesion in the double-transgenic mice as assessed by immunohistochemistry. The double-transgenic, 15-LO-overexpressing, LDL receptor-deficient mice (LDLR-/-/15LO) developed significantly larger atherosclerotic lesions at the aortic sinus compared with lesions in the LDL receptor-deficient (LDLR-/-) mice after 3 and 6 weeks (107,000 versus 28,000 microm(2) [P:<0.001] and 121,000 versus 87,000 microm(2) [P:<0.05], respectively) of an atherogenic diet. LDL from the LDLR-/-/15LO mice was more susceptible to oxidation than was the LDL from the control LDLR-/- mice, as shown by a shorter lag period for copper-induced conjugated diene formation. On the other hand, no differences were found in the levels of serum anti-oxidized LDL antibodies between the study groups. There were also no differences with respect to the density of macrophages and T lymphocytes infiltrating the lesions in both experimental groups. Taken together, these results support the hypothesis that 15-LO overexpression in the vessel wall is associated with enhanced atherogenesis.

A possible role for 15-lipoxygenase in atherogenesis.

It is well accepted that high levels of low-density lipoprotein (LDL) cholesterol in the plasma are associated with increased risk of atherosclerosis. The cellular and molecular mechanisms linking the two however, have not been fully resolved. One of the processes involved in atherogensis that has been intensively studied in this regard is the oxidation of LDL. Oxidation may convert LDL into an atherogenic form, which incites an inflammatory and proliferative response characteristic of the atherosclerotic lesion. One of the potential mediators in this process is the lipid peroxidating enzyme 15-lipoxygenase, which has been shown to be induced in the atherosclerotic lesion and is capable of oxidizing LDL. In this article, we review the motivation for looking at mechanisms of LDL oxidation and the proposed involvement of 15-lipoxygenase in the pathogenesis of the disease.

Interindividual variability in sensitivity to warfarin--Nature or nurture?

BACKGROUND: Interindividual variability in responses to warfarin is attributed to dietary vitamin K, drug interactions, age, or genetic polymorphism in the cytochrome P4502C9 enzyme (CYP2C9) (allelic variants 2C9*2 and 2C9*3 ) linked with impaired metabolism of the potent enantiomere S-warfarin. PATIENTS AND METHODS: We quantified the relative effects of age and of simultaneously determined CYP2C9 genotype, plasma warfarin and vitamin K concentrations, and concurrent medications on warfarin maintenance doses in 156 patients at optimized stable anticoagulation. RESULTS: Allele frequencies for CYP2C9*1, CYP2C9*2, and CYP2C9*3 were 0.84, 0.10, and 0.06. Warfarin doses were 6.5 +/- 3.2, 5.2 +/- 2.4, and 3.3 +/- 2.0 mg/d in the 3 genotype groups (P < .0001). Warfarin doses decreased with age as follows: 7.7 +/- 3.7 versus 4.9 +/- 2.9 mg/d at < 50 years and >66 years (P < .001), mainly as a result of decreased plasma warfarin clearance (2.8 +/- 1.4 mL/min versus 1.9 +/- 0.8 mL/min; P < .001). Vitamin K (1.6 +/- 1.1 ng/mL) did not differ among the age or genotype groups. Patients >or=66 years old with the CYP2C9*3 allele required only 2.2 +/- 1.2 mg/d compared with 7.9 +/- 3.7 mg/d in those

Effects of diets rich in monounsaturated fatty acids on plasma lipoproteins--the Jerusalem Nutrition Study. II. Monounsaturated fatty acids vs carbohydrates.

Seventeen male Yeshiva students were randomly allocated to a crossover study with two 12-wk dietary periods of monounsaturated fatty acids (MUFAs) vs a carbohydrate (CHO)-rich diet while concentrations of saturated (SFAs) and polyunsaturated (PUFAs) fatty acids were kept similar. Total plasma cholesterol (TC) decreased significantly by approximately 7.7% and low-density-lipoprotein cholesterol (LDL-C) by 14.4% on the MUFA diet, whereas on the CHO diet no significant change in cholesterol concentrations occurred, in contrast to that predicted by the equations of Keys and Hegsted. Concentrations of high-density-lipoprotein cholesterol (HDL-C) did not change significantly on either diet. On the MUFA diet there was a significantly lower proneness to peroxidation of plasma and LDL lipids and less extensive metabolism of conditioned LDL by peritoneal macrophages. We conclude that dietary MUFAs lower TC and LDL-C concentrations, independently of other dietary fatty acids and in addition may reduce the susceptibility of LDL to oxidative stress.

Citrus fruit supplementation reduces lipoprotein oxidation in young men ingesting a diet high in saturated fat: presumptive evidence for an interaction between vitamins C and E in vivo.

To determine the effects of vitamin C on cardiovascular risk factors, we studied dietary vitamin C enrichment in 36 healthy male students consuming a diet high in saturated fatty acids. After a 1-mo run-in period during which the subjects consumed approximately 50 mg ascorbic acid/d (low-C diet), half of the subjects were randomly assigned to receive 500 mg ascorbic acid/d for an additional 2 mo (high-C diet). Plasma ascorbic acid increased from 13.5 micromol/L with the low-C diet to 51.7 micromol/L with the high-C diet. Plasma cholesterol increased slightly with the high-C diet, but not above baseline concentrations. This increase was offset by an increase in the lag period of in vitro LDL oxidation, which correlated with plasma ascorbic acid concentrations (r = 0.735, P = 0.0012). Lipoprotein vitamin E concentrations were unchanged with the two diets. There were no effects on concentrations of fibrinogen or factor VII. The fact that ascorbic acid reduced the in vitro susceptibility of lipoproteins to oxidation provides presumptive evidence for an interaction between aqueous and lipophilic antioxidants (vitamins C and E ) in maintaining the integrity of LDL particles.

Emerging cross-regulatory roles of immunity and autoimmunity in atherosclerosis.

Atherosclerosis is a histopathological process of a multifactorial origin. Whereas the genetic and biochemical causes received considerable attention, the involvement of the immune system has generally been considered negligible. In recent years evidence has been presented to support the dominant role played by the immune system in atherosclerosis. Two major antigenic determinants against which the immune response may be triggered have been suggested, namely the heat shock protein 60/65 and oxidized low density lipoprotein. The current paper reviews the data regarding the involvement of the immune system in atherogenesis with respect to the antigenic candidates mentioned above.

Non-obese diabetic (NOD) mice exhibit an increased cellular immune response to glycated-LDL but are resistant to high fat diet induced atherosclerosis.

Diabetes mellitus is one of the major risk factors for atherosclerosis. In recent years several murine models have been developed in an attempt to reproduce the accelerated atherosclerosis by combining induced hyperglycemia with hyperlipidemia. In the present study we wished to examine the effect of spontaneous hyperglycemia and hyperlipidemia induced by high fat diet on atherosclerosis development and on markers of the immune system in diabetes prone NOD mice. We tested two high fat dietary regimens (with or without cholate supplementation) in female NOD mice that either developed or did not develop diabetes. Plasma fasting glucose, lipid profile, antibodies to oxidized-LDL and glycated-LDL were assessed. The spleens from both groups were evaluated for their proliferative response. The extent of atherosclerosis was assessed at the aortic sinus. It was found that the two high fat dietary regimens were insufficient to elicit atherosclerosis in the diabetic and non-diabetic NOD mice. The diabetic hyperlipidemic NOD mice displayed an increased cellular immune response to glycated-LDL in comparison with their non-diabetic littermates. The immune response towards copper oxidized LDL was similar in both groups despite an increased susceptibility of LDL extracted from diabetic hyperlipidemic mice to undergo copper induced oxidation. We conclude that the NOD mouse is highly resistant to atherosclerosis even in the presence of hyperglycemia-hyperlipidemia and increased susceptibility to copper induced LDL oxidation.